What Is 'I Am Number Four' About?

What Is 'I Am Number Four' About?
Based on a bestselling young-adult novel by the same title, 'I Am Number Four' follows a teenage humanoid alien (played by Alex Pettyfer) that hails from the planet Lorien. He goes by John Smith (or Dan Jones, or a bunch of other nondescript names, depending where he moves) and lives with his guardian, Henri (Timothy Olyphant).

John was one of only nine young aliens (plus their keepers) who escaped Lorien before it was destroyed. They were each given a number and a special protective charm that meant they could only be killed in number order; when one is killed, the survivors receive a magical scar on their legs. When the third scar appears on John's leg, he knows he's next to be tracked down by the Mogadorians, the aliens who wiped out life on Lorien and want to do the same on Earth. John and Henri have to outrun the Mogadorians while attempting to remain under the radar in their new adopted small town of Paradise, Ohio.